For a plurality of different applications it can be required to weld two plastic components together. For example, two housing parts can be welded together. For the manufacturing of plastic heat exchangers which, for example, are used for cooling of charge air in a charged internal combustion engine, it can be required to weld a carrier plate to each of the ends of a plurality of individual pipes. Here, in extremely confined space, a plurality of weld joints have to be carried out which, in addition, have to be relatively sealed.
From WO 2007/065271 A1 it is known for a heat exchanger to provide plastic pipes with a radially projecting flange which abuts planar against a carrier plate. At least in the region of the flange, the plastic pipes have a relatively high permeability for a laser beam used during laser welding. In contrast to that, the carrier plate has a relatively low permeability for the laser beam. The laser beam can now pass through the flange perpendicular to the carrier plate and is absorbed only when it reaches the material of the carrier plate, whereby at the interface between the carrier plate and the flange, the desired weld location can be formed. For the implementation of the known method, a relatively large installation space is necessary since the flange has a considerably bigger diameter than the respective pipe.
From U.S. Pat. No. 5,749,414, a method for laser welding two aluminum parts is known. Here, for a heat exchanger, one pipe, respectively, is inserted into a carrier plate until the pipe is flush with the carrier plate. Then, the front-side end of the pipe can be welded to the plate by means of a laser beam.